As is known, Microsystems have emerged as a useful tool in such areas as electronics, research and clinical medicine. Microsystems are considered to be any device or unit made up of a number of microengineered and/or micromachined components, such as miniature pumps and valves. In an attempt to develop Microsystems that perform more complex functions, ongoing research is being conducted in the area of microelectromechanical systems (MEMS). Due to various innovations in the integrated circuit industry (e.g., micromachining), the development of microsystems has progressed rapidly. For example, various microsystems which incorporate microengineered and/or micromachined components such as sensors, actuators, valves and the like are now widely used in academia. These microsystems are designed for various applications, including microfluidics and drug delivery.
Further expansion of the uses for microsystems has been limited due to the difficulty and expense of fabrication. While silicon-based Microsystems have proven well suited to optical and physical sensing applications, the use of silicon-based devices in other applications is not straightforward. Silicon-based approaches typically rely on actuation methods (electrostatic, thermal, electromagnetic) that are not suitable for direct interface with liquid and organic systems. In addition, the integration of microscale valves and other microscale components into micro devices has proven problematic. Often, the manufacturing process that provides a useful microscale valve is vastly different from the manufacturing process that provides a useful microscale pump or sensor. Hence, different device components necessarily require different materials for construction and different types of manufacturing steps. As a result, the integrating of several microengineered components into a single micro device is both time consuming and expensive.
In order to overcome the limitations of prior MEMS technology, polymer-based fabrication techniques have been developed. During polymer-based fabrication, liquid-phase photopolymerization is utilized to allow for the rapid creation of microcomponents. As a result, photosensitive polymers can be patterned within a micro device without the additional necessity of a clean-room environment. Further, liquid-phase photopolymerization is a low-temperature process (<100 degrees Celsius) and allows the fabricator to construct a desired microcomponent at a designated area on a substrate. Hence, it is highly desirable to provide a method of fabricating a micro device that leverages the advantages of both silicon-based Microsystems with polymer-based fabrication techniques.
Therefore, it is a primary object and feature of the present invention to provide a micro device that incorporates a programmable element that functions without on-chip wiring or electricity.
It is a further object and feature of the present invention to provide a micro device that is simple and inexpensive to manufacture.
It is a still further object and feature of the present invention to provide a micro device that may be customized to a particular application without undue additional expense.
In accordance with the present invention, a micro device is provided that includes a body defining a chamber. The chamber has an input and an output for accommodating the flow of fluid therebetween. The micro device includes a moveable element disposed in the chamber and a clutch mechanism engageable with the moveable element for controlling the movement thereof.
The clutch mechanism has a first configuration wherein the moveable element is fixed in position and a second configuration wherein the moveable element is free move along a path. The clutch mechanism includes a polymeric material having a volume responsive to the value of an environmental property such as the pH or temperature of the fluid. The material has a first volume in response to the environmental property having a first value and a second volume in response to the property having a second value.
The moveable element includes a central hub that may have a blade extending radially therefrom and an opening therein for receiving the polymeric material. The opening is defined by an inner hub surface that is engaged by the polymeric material when the polymeric material has the second volume. As a result, the polymeric material prevents movement of the moveable element.
In a first embodiment, the blade has a terminal end radially spaced from and interconnected to the central hub by a generally arcuate edge. Alternatively, the blade may include first and second edges extending radially from the central hub and diverging from each other. It is contemplated for an alternate embodiment of the moveable element to include a radially outer edge having a plurality of teeth circumferentially spaced thereabout.
In accordance with a further aspect of the present invention, a micro device is provided that includes a body defining a chamber. The chamber has an input and an output for accommodating the flow of fluid therebetween. A rotational element is disposed in the chamber. The rotation element includes a central hub and is rotatable about an axis. A clutch mechanism is engageable with the rotational element in response to an environmental property. The clutch mechanism controls rotation of the rotational element.
The central hub of the rotational element has an opening therethrough for receiving a post disposed in the chamber. The clutch mechanism includes a polymeric material that extends about the post and that has a volume responsive to the value of the environmental property, such as the pH or temperature of the fluid. The polymeric material has a first volume in response to the property having a first value and a second volume in response to the property having a second value. The opening through the central hub of the rotational element is defined by an inner hub surface. In its second volume, the polymeric material engages the inner hub surface and prevents rotation of the rotational element.
In a first embodiment, the blade has a terminal end radially spaced from and interconnected to the central hub by a generally arcuate edge. Alternatively, the blade may include first and second edges extending radially from the central hub and diverging from each other. An alternate embodiment of the rotational element includes a radially outer edge having a plurality of teeth circumferentially spaced thereabout.
In accordance with a still further aspect of the present invention, a micro device is provided. The micro device includes a body defining a chamber for receiving fluid. A moveable element is disposed in the chamber and is moveable along a predetermined path in response to an external stimulus. The micro device further includes a clutch mechanism having a first disengaged configuration and a second engaged configuration wherein the clutch mechanism engages the moveable element.
The clutch mechanism is movable between the disengaged configuration and the engaged configuration in response to an environmental property, such as the pH or temperature of the fluid. The moveable element includes a central hub having an opening therethrough for receiving a post disposed in the chamber. The clutch mechanism includes polymeric material extending about the post. The polymeric material has a volume responsive to the value of the environmental property. The polymeric material is spaced from the moveable element with the clutch mechanism in the first disengaged configuration and the polymeric material engages the moveable element with the clutch mechanism in the second engaged configuration.
The body defines a first input channel having an output communicating with the chamber and an output channel having an input communicating with the chamber. In a first embodiment, the body may define a second input channel having an output communicating with the chamber. Alternatively, the body may define a feedback channel having an input communicating with the output channel downstream of the chamber and an output communicating with the input channel upstream of the chamber.